Songs typically feature high-pitched melodies with deeper bass lines. While listeners are capable of hearing both sets of frequencies, of course, we may be better equipped to pick up on the rhythm set by the deep bass sounds.

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McMaster student Kristin Tonus tries on sensors at the McMaster Institute for Music and the Mind. Director Laurel Trainor and colleagues have been studying why we appreciate strong bass rhythms in a song.

In the study, Trainor and her colleagues monitored electrical activity in the brains of 35 people. The researchers played a sequence of low- and high-pitched piano notes at the same time, and every so often, the notes were played 50 milliseconds too fast. The vast majority of the people were better able to detect the offbeat in the lower tone.

Then the researchers asked another group of men and women to tap their fingers to the rhythm of the same tonal sequences. When the timing change occurred, the researchers noticed that the people were more likely to modify their tapping to fall in sync with the low-pitched tone.

Next, the researchers played those sequences through a computer model of the human ear. What did they find?

The model ear, too, recognized the offbeat in the low-pitched tone more often than it did in the higher tone, leading researchers to speculate that the effect arises within the ear itself.

While some music lovers may be better at following rhythm than other "beat deaf" people, the researchers also found that the ability to discern offbeat timing between tones emerges early as the brain processes the sound.

This study "provides a very plausible hypothesis for why bass parts play such a crucial role in rhythm perception," Dr. Tecumseh Fitch, a University of Vienna cognitive scientist who did not participate in this research, told Nature.

The study was published online Monday in Proceedings of the National Academy of Sciences.

Wellcome Trust employee Zoe Middleton poses for the media by a work entitled 'My Soul' by artist Katherine Dawson, that is a laser etched in lead crystal glass of the artist's own MRI scan, at an exhibition call 'Brains -The Mind as Matter' at the Wellcome Collection in London, Tuesday, March, 27, 2012. The free exhibition is open to the public from March 29- June 17. (AP Photo/Alastair Grant)